Abstract:An analysis of the structure features and the heavy rainfall of landing typhoon Maisha during 6—9 Aug. 2005 are performed with the dense observational data, the satellite TBB data and NCEP re-analysis data. The results show that the typhoon maintained extinguish asymmetry structure and had stronger convective clouds in the east and north of the typhoon during its long distance travel in East China. The surface vorticity and divergence fields were asymmetric. The center of surface positive vorticity located mainly in the east of typhoon and moved to northeast part of the typhoon as its northward walking. A strong convergent region extended northward accompanied the surface inverted trough. The 850 hPa winds in east and north of the typhoon were stronger than that in other direction, a strong easterly low-level jet sustained in north of the typhoon. The eastern part of the typhoon was warm and the western was cold, there was strong warm advection in the northeast of the typhoon due to the asymmetry of flow and thermal fields. The development of the 200 hPa upper level jet and the upper level divergence generated in right side of this jet exit region provided good dynamical conditions to the typhoon when it was traveling in East China for the long time and was helpful to maintain its intensity. The ascending motion in 500hPa is directly associated with the area of heavy rain caused by the typhoon.